Expansible bit.



Patgnted Apr'. 3, I900.

.1. P. LAVI GNE. EXPANSIBLE BIT. (Apph c' 'mease 15 1899) (No Model.)

JQSEPTH P. LAVIGNE, OF NE? HAVEN, CONNECTICUT, ASSIGNOR TO JOHN J.TOWER, OF NEWV YORK, N. Y.

EXPANSIBLE BIT.

SPECIFICATION forming part of Letters Patent No. 646,439, dated April 3,1900.

Application filed September 15, 1899- Serial No. 730,532. (No model.)

such as will enable others skilled in the art to which it appertains tomake and use the same, reference being had to the accompanying drawings,and to the letters of reference marked thereon, which form a part ofthis specification.

Expansible bits of the type to which my present invention relates havebeen made with the head and shank integral, a radiallyextensible cuttermounted in a recess transversely of said head and held in place byeither a separate or integral clamp-plate, and a screw passed throughthe same. Still others have been made with the shank and head integral,a radially-extensible cutter mounted in a recess transversely of saidhead and held in place by a vertically-slidable clamp-plate, and aninternally-screw-threaded sleeve operating on screw-threads chased upona portion of the head. Several disadvantages have been encountered inthese forms, among which are the weakening of the head by the necessityof cutting away much of the body thereof in order to accommodate thecutter and clamps and the difficulty of making the clamp-screws or thescrew-threaded sleeves maintain their grip. These forms, moreover, areexpensive of manufacture.

The objects of my present invention are to overcome these severalobjections and to improve such tools in several other particularshereinafter shown.

My present invention therefore consists, mainly, in an expansible bitcomprising a shank having its lower end suitably threaded to screw intoa tubular removable internallyscrew-threaded head, a lead-screw, asuitable recess transversely of said head for reception of aradially-extensible cutter, the bore of said head connecting saidcutter-recess and said internally-sorew-threaded portion thereof, and aslug or pin slidably fitted in said bore or tubular portion'of the headand provided with a bevel at one end and in some cases with a shoulderand spring at the other view of the head with cutter and shank re-'moved; Fig. 6, a top end view of the head with cutter and shank removed;Fig. 7, a perspective view of the slugor pin. Figs. Sand 9 and 10 and 11are respectively end and side elevations of cutters of differentlengths, and Fig. 12 illustrates a modification of parts of myinvention.

Like letters indicate corresponding parts throughout the severalfigures.

A is the shank; a, the screw-threads at its lower end.

B is the head; I), a transverse two-Way inclined wedge shaped recesstransversely therein for reception of the radially-extensible cutter c;b, a round hole intersected by said wedge-shaped recess tangentially onthe upper side, but having its radius depressed below the base of thelower side of said recess to form a ridge or hook at 11'.

C is the bore of the tubular portion of the head, which islongitudinally central with the lead-screw d for reception of the slugor pin D, and c is a counterbored portion of said bore 0, screw-threadedforreception of the screw-threaded end a of said shank.-

@ is a lever-socket in the rear of the head 13.

f is an inclined surface or bevel on the lower end of the slug or pin.

g g are graduations on the face of the cutter, and h is the usual spuratthe outer end thereof.

2' is the extended roll-surface of the cutterback, which forms a beadand serves to hook upon the raised ridge Z within the recess 1).

The functions of the several parts will hereinafter appear.

The operation of my present invention is as follows: Having beenconstructed and assembled as shown, the cutter c is placed in theposition required to bore a hole of the diameter desired, which may beaccurately indicated by the outer cornerj of the head registering withthe appropriate graduation g. The head B is now held from turning whilethe shank A is screwed down into it, which operation forces the bevel fof the slug or pin D firmly against the inclined face of the cutter c,which latter, being hooked at t 1" against sliding downward or outward,is thereby instantly and'firmly bound in place and securely held againstradial displacement. It will now clearly appear to those skilled in theart that when the bit is applied the act of boring serves to furthertighten the cutter, because if there be any rotation whatever of thehead B on the screw-threaded end a of the shank A it must of courseforce the slug or pin D against the cutter c and more firmly impinge thelatter on its seat and at i i.

As a provision for holding the head B when tightening the cutter inplace or when unscrewing the shank A to release the same a socket e ismade, preferably on the rear side of the head, so that a lever, a nail,or a bit of wire may be inserted therein.

I prefer to make the head in the form shown, with its front 71 reducedby a circle of greater radius than that of the circle of the rear side,(see Fig. 3,) but do not wish to limit myself to tli'is.

Fig. 12 shows a modified construction of the slug or pin D to permit ofthe application of a coiled spring 7c upon the reduced end, one end ofsaid spring to bear against the shoulder Z of the pin and the otheragainst the threaded end a of the shank A. It will be understood thatthe object of this is to keep the beveled end f of the pin in frictionalcontact with the cutter 0, so that when being loosened for adjustmentthe latter may not fall out of the recess 1). This feature of myinvention may or may not be employed.

Having described my invention, what I claim as new, and desire to secureby Letters Patent, is-

1. In an expansible bit, in combination, a shank screw-threaded at itslower end, a revoluble, tubular head internally screw-threaded at itsupperend, a slug or pin to act in said tubular head, and aradially-extensible cutter carried in a suitable recess in said head,substantially as set forth.

2. In an expansible bit, in combination, a shank screw-threaded at itslower end, a revoluble, tubular head internally screw-threaded at itsupper end, a slug or pin to act in said tubular head shouldered at oneend, a coiled spring bearing against said shoulder, and aradially-extensible cutter carried in a suitable recess in said head,substantially as set forth. I

3. In an expansible bit, in combination, a shank screw-threaded at itslower end, a revoluble, tubular head internally screw-threaded at itsupper end, and provided with a lever-socket in one side thereof, a slugor pin to act in said tubular head, and a radiallyextensible cuttercarried in a suitable recess in such head, substantially as set forth.

4. In an expansible bit, in combination, a shank screw-threaded at itslower end, a revoluble, tubular head internally screw-threaded at itsupper end, a slug or pin to act in said tubular head, and aradially-extensible cutter, having a roll-bead i along its back, carriedin a recess in said head, wherein is provided a ridge or hook 1; on itslower'wall, substantially as described.

5. The herein-described improved expansible bit, comprising a shankscrew-threaded at its lower end, a revoluble, tubular head, internallyscrew-threaded at its upper end, a slug or pin to act in said tubularhead pro vided with a bevel at one end, a lead-screw, aradially-extensible, graduated cutter, having a spur at its outer endand a roll-bead f along its back, carried in a recess in said head,wherein is provided a ridge or hook t" on its lower wall, substantiallyas described.

6. The herein-described improved expansible bit comprising a shank,screw-threaded at its lower end, a revoluble, tubular head, internallyscrew-threaded at its upper end, a slug or pin to act in said tubularhead, having a bevel at one end and a shoulder at its other end, acoiled spring bearing on said shoulder, a lead-screw, aradially-extensible, graduated cutter, having a spur at its outer endand a roll-bead 1' along its back, carried in a recess in said head,wherein is provided a ridge or hook t" on its lower wall, substantiallyas set forth.

In testimony whereof I affix my signature in presence of two witnesses.

J OSEPTH P. LAVIGNE.

Witnesses:

JOHN J. TOWER, WILLIAM H. COLE.

